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Dental size traits within families: Path analysis for first molar and lateral incisor
Author(s) -
Potter Rosario H. Yap,
Rice John P.,
Dahlberg Albert A.,
Dahlberg Thelma
Publication year - 1983
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.1330610302
Subject(s) - incisor , molar , sibling , path analysis (statistics) , intraclass correlation , orthodontics , biology , evolutionary biology , demography , mathematics , statistics , ecology , psychology , medicine , developmental psychology , sociology , psychometrics
Abstract Previous works on the inheritance of dental traits have traditionally followed Fisher's model for family data under the assumption that phenotypic similarity between relatives is due solely to genetic factors. This study uses recent causal models that incorporate the contribution of nonrandom environmental sources of variation to familial resemblance on dental size. Path analysis was applied to observed interclass and intraclass correlations of sex‐specific parent‐offspring and sib pairs in 293 Pima Indian families from the southwest United States. The mesiodistal dimension of an early‐forming and stable tooth (first molar) was contrasted with a late‐forming and variable tooth (upper lateral incisor) for genetic and familial environmental components of variation. Parameters were estimated according to the XTAU models of Rice et al. (1980) and linear constraints placed upon the parameters were tested. The proportion of variance accounted for by genetic and environmental transmissible factors is estimated to be 52% for the first molar and 35% for the lateral incisor. Neither X‐linkage nor sex‐specific environmental effects are required to explain the transmission of dental size. Nontransmissible environmental effects that account for sibling correlations are detectable. Furthermore, sex differences are found in correlated sibling environments for the lateral incisor but not the first molar, to explain in part male‐female differences in the distributions of the upper lateral incisor size.